Roebling’s aqueduct is one of the oldest surviving suspension bridges in United States. Running 535 feet (175 m) from Minisink Ford, New York to Lackawaxen, Pennsylvania it is one of the four suspension aqueducts on the Delaware and Hudson Canal (D & H). John A. Roebling, the designer and constructor of this historic suspension aqueduct was the builder of one of the most notable suspension bridges in United States of America, The Brooklyn Bridge. As the industrial revolution started spreading the demands for production in all branches of manufacturing increased. Following the increased demand in manufacturing was the increased demand of transportation. Coal which was the major source of energy throughout the nineteenth century also saw great rise in demand as the industrial growth sustained and spread. At the same time in history in northern Pennsylvania, the Delaware and Hudson (D&H) canal saw some serious concerns regarding the transportation system being used; Vessel transportation of heavy freight along the canal. The D&H canal was one of the biggest and the most used means of transportation for the entire eastern Pennsylvania. The canal was used for vessels going down all the way to Philadelphia or Trenton starting up north. Transportation of slightly smaller commodities when compared to the heavy freight along the canal was the transportation of timber and other smaller commodities using a rope ferry across the canal.
The rope ferry being used across river always experiences the force of the current not in the favor of the ferry being tugged across the river. Hence the rope ferries are always used where the canal takes the thinnest course to reduce the resistance from the current. The rope ferry across the D&H had a bigger problem than the force of the current- the growing heavy freight transportation along the canal. Since the ferry was used across a relatively thinner section of the canal, the conflicting traffic caused a severe bottle-neck situation. The traffic along the canal increased in great proportions by the 1830s when the industrial growth was at its peak. By the 1840s the D&H was looking into ways which could speed up the traffic along the canal and reduce the traffic conflict. The solution for this subject had to be fairly simple and innovative. The solution had to be simple because the soil on the banks of the canal cannot support a heavy architecture. Later in this paper I have presented information about latest restoration work carried out at the aqueduct which shows the soil limitations of the site. The design of the bridge cannot be a simple roadway bridge as we need to keep in mind road transportation did not even begin mass manufacturability for transportation till the advent of Model T in early 1900s which was just a two seater. The only reliable transport even for transportation across the canal was still water. To solve this issue, John Roebling who was commissioned for this project decided on and aqueduct across the river which could still allow a canal boat across the river on the water which flowed through the main trunk of the aqueduct.
“The sight of a canalboat crossing a river was hardly remarkable in 1849 when, on April 26, a local crowd and engineers from all over the country gathered on the banks of the Delaware River in upper Pennsylvania. The boat in view was an ordinary barge. What was curious was how it got from shore to shore—floating inside a wooden flume suspended thirty feet above the water from two iron cables, which dipped across the river over stone piers.
The flume, or trunk, held the waters of the Delaware & Hudson Canal, which had been routed right through Lackawaxen into New York State on the opposite bank. The aqueduct’s designer, the forty-two-year-old John A. Roebling—who later designed the Brooklyn Bridge—couldn’t possibly have foreseen the uses to which this creation, his third suspension structure ever, would later be put.”[2]
The figure 1 shows the cross sectional drawing of the Roebling’s aqueduct showing the trunk line and the canal water level.
5.png
Usage of rope-wires:
Roebling, for the suspension aqueduct used the rope-wire technology which has never been used before suspension architecture. Roebling first used his concept of rope-wires in the aqueduct at Pittsburg which was built before the Roebling’s aqueduct in Pennsylvania. When the project at Lackawaxen was being commissioned there were attempts made by his competition challenging his calculations and new concepts. There were fliers being circulated questioning the $ 41,750 commission for the project being handed over to Roebling. There wasn’t a great response to the revolt however as the Roebling was acknowledged with his hand-written specifications for the Pittsburg aqueduct and the successful usage of the aqueduct. “On August 12, 1844, Roebling filed an acceptable 27-page handwritten set of specifications for the aqueduct with the Canal Commission, detailing the design, the materials and the calculations on which the design was based. The calculations are remarkably simple, but these are the basic principles for today’s suspension bridges. By April of the next year, the job was done.”[3].
The engineering competence in the Roebling’s designs could be justified by the other designs adapting Roebling’s designs. After the failure of the Tochickon Aqueduct Failure in 1932, the new Tohickon Aqueduct could not be designed as a suspension structure; and a truss constructed above the trunk would create a series of new problems. SJ/DC determined to place the trunk between the two trusses, and borrow the slanted wall trunk design from the Roebling Aqueduct. This configuration served two purposes: the sloped walls reduced the volume of water to be carried; and also served as lateral bracing for the trusses.[4]
1.png
6.png
After establishing the engineering competence in the Roeblings’s designs, I want to evaluate the need of building the project and the need of restoring which began in 1986. The biggest reasons behind the decline of the usage of the Roebling’s aqueduct was contributed the increased usage of railways in the United States. The first transcontinental rail road was started in the year 1869. Though there have been earlier usages of railways for transportation. No large scale rail lines had even surfaced till the mid 1800s when the Roebling’s aqueduct was sanctioned. Despite an established railway network being started in 1869, the Roebling’s aqueduct was being used to a great extent till the 1898 which is roughly one quarter a century after the railways have been established in United States. In today’s world we have the biggest of the companies and corporations working on a five year plan. Keeping that in mind, it is more than acceptable to say that the Roebling’s project was a wise investment of money which facilitated to the industrial growth of 19th century in the eastern Pennsylvania region.
First attempts of restoration of the Roebling’s aqueduct began in 1986. The National Parks services made a commitment to open the Roebling aqueduct which is now a bridge to the vehicular traffic. The agency spent $26,000 for the restoration process. Even after this initial phase of restoring, the aqueduct needed a second phase of restoring constituting the poor soil quality which further affected by the flooding. The following two pictures show the condition of the bride main columns before and after the second phase of restoring.
Before Phase 2 of restoration
Before Phase 2 of restoration
After Phase 2 of restoration
After Phase 2 of restoration
An interesting fact about the quality of college students in United States was compared with the quality of students in countries like Indian and China. It is believed that India has more scholarly students than the number of students going to college in USA. Though the figures are scary, there is a valid reason behind the incomparable success of engineering companies in United States to those in India. Students here are encouraged to apply the knowledge in real world. The case of Roebling’s aqueduct is one of the classic examples. The second phase of restoration had civil engineering college interns assisting the restoration and gaining solid experience in soil engineering while assisting in the project. This is a great way to maintain historic contingency. If we chose to not take care of historic projects like this there could be a breakage in the link of education and what students learn in the future, the link that connects the historic architecture to modern engineering expertise. Hence I strongly believe that the restoration of the project is a great initiative by the national park service taken up in trying to keep the historic constructions alive.
Roebling's Aqueduct
Roebling’s aqueduct is one of the oldest surviving suspension bridges in United States. Running 535 feet (175 m) from Minisink Ford, New York to Lackawaxen, Pennsylvania it is one of the four suspension aqueducts on the Delaware and Hudson Canal (D & H). John A. Roebling, the designer and constructor of this historic suspension aqueduct was the builder of one of the most notable suspension bridges in United States of America, The Brooklyn Bridge. As the industrial revolution started spreading the demands for production in all branches of manufacturing increased. Following the increased demand in manufacturing was the increased demand of transportation. Coal which was the major source of energy throughout the nineteenth century also saw great rise in demand as the industrial growth sustained and spread. At the same time in history in northern Pennsylvania, the Delaware and Hudson (D&H) canal saw some serious concerns regarding the transportation system being used; Vessel transportation of heavy freight along the canal. The D&H canal was one of the biggest and the most used means of transportation for the entire eastern Pennsylvania. The canal was used for vessels going down all the way to Philadelphia or Trenton starting up north. Transportation of slightly smaller commodities when compared to the heavy freight along the canal was the transportation of timber and other smaller commodities using a rope ferry across the canal.
The rope ferry being used across river always experiences the force of the current not in the favor of the ferry being tugged across the river. Hence the rope ferries are always used where the canal takes the thinnest course to reduce the resistance from the current. The rope ferry across the D&H had a bigger problem than the force of the current- the growing heavy freight transportation along the canal. Since the ferry was used across a relatively thinner section of the canal, the conflicting traffic caused a severe bottle-neck situation. The traffic along the canal increased in great proportions by the 1830s when the industrial growth was at its peak. By the 1840s the D&H was looking into ways which could speed up the traffic along the canal and reduce the traffic conflict. The solution for this subject had to be fairly simple and innovative. The solution had to be simple because the soil on the banks of the canal cannot support a heavy architecture. Later in this paper I have presented information about latest restoration work carried out at the aqueduct which shows the soil limitations of the site. The design of the bridge cannot be a simple roadway bridge as we need to keep in mind road transportation did not even begin mass manufacturability for transportation till the advent of Model T in early 1900s which was just a two seater. The only reliable transport even for transportation across the canal was still water. To solve this issue, John Roebling who was commissioned for this project decided on and aqueduct across the river which could still allow a canal boat across the river on the water which flowed through the main trunk of the aqueduct.
“The sight of a canalboat crossing a river was hardly remarkable in 1849 when, on April 26, a local crowd and engineers from all over the country gathered on the banks of the Delaware River in upper Pennsylvania. The boat in view was an ordinary barge. What was curious was how it got from shore to shore—floating inside a wooden flume suspended thirty feet above the water from two iron cables, which dipped across the river over stone piers.
The flume, or trunk, held the waters of the Delaware & Hudson Canal, which had been routed right through Lackawaxen into New York State on the opposite bank. The aqueduct’s designer, the forty-two-year-old John A. Roebling—who later designed the Brooklyn Bridge—couldn’t possibly have foreseen the uses to which this creation, his third suspension structure ever, would later be put.”[2]
The figure 1 shows the cross sectional drawing of the Roebling’s aqueduct showing the trunk line and the canal water level.
Roebling, for the suspension aqueduct used the rope-wire technology which has never been used before suspension architecture. Roebling first used his concept of rope-wires in the aqueduct at Pittsburg which was built before the Roebling’s aqueduct in Pennsylvania. When the project at Lackawaxen was being commissioned there were attempts made by his competition challenging his calculations and new concepts. There were fliers being circulated questioning the $ 41,750 commission for the project being handed over to Roebling. There wasn’t a great response to the revolt however as the Roebling was acknowledged with his hand-written specifications for the Pittsburg aqueduct and the successful usage of the aqueduct.
“On August 12, 1844, Roebling filed an acceptable 27-page handwritten set of specifications for the aqueduct with the Canal Commission, detailing the design, the materials and the calculations on which the design was based. The calculations are remarkably simple, but these are the basic principles for today’s suspension bridges. By April of the next year, the job was done.”[3].
The engineering competence in the Roebling’s designs could be justified by the other designs adapting Roebling’s designs.
After the failure of the Tochickon Aqueduct Failure in 1932, the new Tohickon Aqueduct could not be designed as a suspension structure; and a truss constructed above the trunk would create a series of new problems. SJ/DC determined to place the trunk between the two trusses, and borrow the slanted wall trunk design from the Roebling Aqueduct. This configuration served two purposes: the sloped walls reduced the volume of water to be carried; and also served as lateral bracing for the trusses.[4]
First attempts of restoration of the Roebling’s aqueduct began in 1986. The National Parks services made a commitment to open the Roebling aqueduct which is now a bridge to the vehicular traffic. The agency spent $26,000 for the restoration process. Even after this initial phase of restoring, the aqueduct needed a second phase of restoring constituting the poor soil quality which further affected by the flooding. The following two pictures show the condition of the bride main columns before and after the second phase of restoring.
References:
[1] http://www.bridgemeister.com/bridge.php?bid=30
[2] http://www.americanheritage.com/articles/magazine/it/1986/1/1986_1_8_print.shtml
[3] http://www.matcoinc.com/files/PublicationPDFs/HOWROEBLINGDIDIT.pdf
[4] http://www.fpl.fs.fed.us/documnts/pdf1996/colli96a.pdf
[5] http://www.drystone.org/gallery/album27/UPDERoeblingJuly2006_003
[6] http://www.drystone.org/gallery/album27/Roebling_NY_2007_12_08_jw_007